In general, the human body includes various lumens, such as a trachea, arteries, blood vessels, as well as urinary, biliary, esophageal or renal tracts, etc. These lumens sometimes become occluded or weakened, or otherwise in need of structural support. For example, the body lumen can be constricted by a tumor, occluded by plaque, or weakened by an aneurysm. For instance, tracheobronchomalacia or TBM is a condition characterized by flaccidity of the cartilage that supports the trachea. This leads to tracheal collapse which in some instances may extend further to the bronchi. TBM may cause discomfort in swallowing, coughing, and breathing to the patient. However, such a condition of the patient can be treated with a medical endoprosthesis to help support the trachea.
Endoprostheses have been developed that may be implanted in a passageway or lumen in the body. In general, such endoprostheses are tubular members with a circular cross-section, examples of which include stents, stent grafts, covered stents, etc. However, such endoprostheses may not be suitable for lumens such as tracheae having non-circular cross-sections, such as a D-shaped cross-section, which requires continued functionality of the trachealis muscle to permit the flow of mucus therethrough, for example.
For instance, the trachea, which lies adjacent to esophagus, has a flat posterior wall which may be pressed by a circular stent, impeding the functionality of the trachealis muscle. In some other instances, existing stents may not be suitable for deployment in branching airways, as the stenting may block side branching airways in the bronchi, for example. In addition, the stents may not allow mucus clearing. Hence, there may exist a need of stents or endoprostheses that may provide desired luminal support while preserving other functionality of the body lumen.